Investigations of the effects of temperature and initial sample pH on natural organic matter (NOM) removal with electrocoagulation using response surface method (RSM)

The removal of natural organic matter (NOM) from surface water by electrocoagulation (EC) was studied using response surface method (RSM). Factors used in the empirical model were electric charge per liter, initial pH and temperature. Relevant square and interaction terms of factors were studied. Based on analysis of variance (ANOVA), the model fitted well with dissolved organic carbon (DOC) reduction, aluminum dissolving and pH changes. UV 254 nm absorbance removal was moderately predicted. According to results, temperature affected significantly the dissolving rate of aluminum electrodes. Initial DOC concentration of the surface water was 18.35 mg/l. Maximum DOC removal of 80.4% was obtained when high electric charge per liter (144 C/l), low pH (4.3) and high temperature (295.15 K) were used. However, high DOC removal of 76.2% was predicted also when water temperature was only 275.15 K. Effect of temperature on NOM removal was minor as compared to the effects of electric charge per volume and the initial pH. EC neutralized pH during the EC treatment and had little impact on the conductivity of the water. According to the results, EC can be used for NOM removal during cold water period in Nordic countries.